/**
 * openHAB, the open Home Automation Bus.
 * Copyright (C) 2011, openHAB.org <admin@openhab.org>
 *
 * See the contributors.txt file in the distribution for a
 * full listing of individual contributors.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses>.
 *
 * Additional permission under GNU GPL version 3 section 7
 *
 * If you modify this Program, or any covered work, by linking or
 * combining it with Eclipse (or a modified version of that library),
 * containing parts covered by the terms of the Eclipse Public License
 * (EPL), the licensors of this Program grant you additional permission
 * to convey the resulting work.
 */

package org.openhab.io.net.actions;

import java.net.MalformedURLException;
import java.net.URL;
import java.util.Dictionary;

import org.apache.commons.lang.StringUtils;
import org.apache.commons.mail.DefaultAuthenticator;
import org.apache.commons.mail.Email;
import org.apache.commons.mail.EmailAttachment;
import org.apache.commons.mail.EmailException;
import org.apache.commons.mail.MultiPartEmail;
import org.apache.commons.mail.SimpleEmail;
import org.osgi.service.cm.ConfigurationException;
import org.osgi.service.cm.ManagedService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/** 
 * This class provides static methods that can be used in automation rules
 * for sending emails via SMTP. 
 * 
 * @author Kai Kreuzer
 * @since 0.4.0
 *
 */
public class Mail implements ManagedService {
	
	static private final Logger logger = LoggerFactory.getLogger(Mail.class);
	
	private static boolean initialized = false;
	
	private static String hostname;
	private static Integer port;
	private static String username;
	private static String password;
	private static String from;

	private static boolean tls;

	/**
	 * Sends an email via SMTP
	 * 
	 * @param to the email address of the recipient
	 * @param subject the subject of the email
	 * @param message the body of the email
	 */
	static public void sendMail(String to, String subject, String message) {
		sendMail(to, subject, message, null);
	}

	/**
	 * Sends an email with attachment via SMTP
	 * 
	 * @param to the email address of the recipient
	 * @param subject the subject of the email
	 * @param message the body of the email
	 * @param attachmentUrl a URL string of the content to send as an attachment
	 */
	static public void sendMail(String to, String subject, String message, String attachmentUrl) {
		if(initialized) {
			Email email = new SimpleEmail();
			if(attachmentUrl!=null) {
				// Create the attachment
				  try {
					  email = new MultiPartEmail();
					  EmailAttachment attachment = new EmailAttachment();
					  attachment.setURL(new URL(attachmentUrl));
					  attachment.setDisposition(EmailAttachment.ATTACHMENT);
					  attachment.setName("Attachment");
					  ((MultiPartEmail) email).attach(attachment);
				} catch (MalformedURLException e) {
					logger.error("Invalid attachment url.", e);
				} catch (EmailException e) {
					logger.error("Error adding attachment to email.", e);
				}
			}

			email.setHostName(hostname);
			email.setSmtpPort(port);
			email.setTLS(tls);
			if(username!=null && !username.isEmpty()) {
				email.setAuthenticator(new DefaultAuthenticator(username, password));
			}
			try {
				email.setFrom(from);
				email.addTo(to);
				if(!StringUtils.isEmpty(subject)) email.setSubject(subject);
				if(!StringUtils.isEmpty(message)) email.setMsg(message);
				email.send();
				logger.debug("Sent email to '{}' with subject '{}'.", to, subject);
			} catch (EmailException e) {
				logger.error("Could not send e-mail to '" + to + "‘.", e);
			}
		} else {
			logger.error("Cannot send e-mail because of missing configuration settings. The current settings are: " +
					"Host: '{}', port '{}', from '{}', useTLS: {}, username: '{}', password '{}'",
					new String[] { hostname, String.valueOf(port), from, String.valueOf(tls), username, password} );
		}
	}

	@SuppressWarnings("rawtypes")
	@Override
	public void updated(Dictionary config) throws ConfigurationException {
		if(config!=null) {
			Mail.hostname = (String) config.get("hostname");
			String portString = (String) config.get("port");
			if(portString!=null) {
				Mail.port = Integer.valueOf(portString);
			}
			Mail.username = (String) config.get("username");
			Mail.password = (String) config.get("password");
			Mail.from = (String) config.get("from");
			Mail.tls = ((String) config.get("tls")).equalsIgnoreCase("true");
			
			// check mandatory settings
			if(hostname==null || hostname.isEmpty()) return;
			if(from==null || from.isEmpty()) return;
			
			// set defaults for optional settings
			if(port==null) {
				port = tls ? 587 : 25;
			}
			initialized = true;
		}
	}
}
